Re: Char device write repeating
On Tue, Oct 04, 2016 at 05:05:57PM +0200, Greg KH wrote: On Tue, Oct 04, 2016 at 10:58:16AM -0400, Kenneth Adam Miller wrote: I have a character device that I am calling write on and which is succeeding, but which is repeatedly executing. I have hard coded the return value to one, Correct me if I'm wrong, I'm just a self-thought newbie, but this ^^ sounds to me like the problem. Because the write should return how many bytes were written (or error), the function is being called until it's been all written. If you just want to be called once and you don't care what the data are (which is the weird thing in the first place), I think you should return the length you got as an argument. so I don't think the userland standard library is retrying but I could be wrong. Can anybody tell me why write would be re-executed by the kernel and how to fix it? I dont actually copy_from_user, I just need this in order to signal kernel land. Do you have a pointer to your code somewhere? This is a very common bug that people have... thanks, greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies signature.asc Description: Digital signature ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Char device write repeating
Because the libc is calling it again based on what has been passed as argument and what was received as return value. Here is one example https://gist.github.com/gkos/5479135. I don't really know if this code is working since I made it a long time ago. Regards, 2016-10-04 12:05 GMT-03:00 Greg KH : > On Tue, Oct 04, 2016 at 10:58:16AM -0400, Kenneth Adam Miller wrote: > > I have a character device that I am calling write on and which is > succeeding, > > but which is repeatedly executing. I have hard coded the return value to > one, > > so I don't think the userland standard library is retrying but I could be > > wrong. Can anybody tell me why write would be re-executed by the kernel > and how > > to fix it? I dont actually copy_from_user, I just need this in order to > signal > > kernel land. > > Do you have a pointer to your code somewhere? This is a very common bug > that people have... > > thanks, > > greg k-h > > ___ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > -- *"Do or do not. There is no try"* *Yoda Master* ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Char device write repeating
On Tue, Oct 04, 2016 at 10:58:16AM -0400, Kenneth Adam Miller wrote: > I have a character device that I am calling write on and which is succeeding, > but which is repeatedly executing. I have hard coded the return value to one, > so I don't think the userland standard library is retrying but I could be > wrong. Can anybody tell me why write would be re-executed by the kernel and > how > to fix it? I dont actually copy_from_user, I just need this in order to signal > kernel land. Do you have a pointer to your code somewhere? This is a very common bug that people have... thanks, greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Char device write repeating
I have a character device that I am calling write on and which is succeeding, but which is repeatedly executing. I have hard coded the return value to one, so I don't think the userland standard library is retrying but I could be wrong. Can anybody tell me why write would be re-executed by the kernel and how to fix it? I dont actually copy_from_user, I just need this in order to signal kernel land. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
